There have been proposed various types of vibration damping system, such as a vibration damping system for protecting buildings from earthquakes, a vibration damping system arranged between a bridge and bridge piers, a vibration damping system for a vibration generating section of a vehicle, such as an engine, and a vibration damping system for a suspended elements. For example, there is known a vibration damping system that includes a laminated body wherein a plurality of hard plates having rigidity and a plurality of soft members having viscoelasticity are alternately laminated with each other, and a pair of shoe plates that are arranged on both end portions in the laminating direction of the laminated body. Such a vibration damping system has high durability against compression force in the laminating direction, and is thus used in various application fields. However, while exhibiting high durability against compression force in the laminating direction, the vibration damping system of the type wherein hard plates and soft members are alternately laminated with each other is very weak to tensile force in the laminating direction. In view of such a problem, as disclosed in JP 2006-057833A, for example, the applicant already proposed a vibration damping system including a displacement restriction member in the form of a chain, so as to provide improved durability to tensile force in the laminating direction.
The vibration damping system disclosed in JP 2006-057833A is explained below with reference to FIG. 6. This vibration damping system 110 includes a laminated rubber body 116 arranged between lower and upper shoe plates 118, 120 as being applied with predetermined pre-compression in the laminating direction, and a displacement restriction member in the form of a link chain 128 connecting the lower and upper shoe plates 118, 120. Here, the laminated rubber body 116 is comprised of hard plates 112 and soft members in the form of rubber plates 114, which are alternately laminated with each other. The laminated rubber body 116 can be placed under a pre-compressed state, by tightening a nut 140 to a bold shaft 136 at the upper end portion of the link chain 128 between the lower and upper shoe plates 118, 120.
With such configuration of the vibration damping system according to the applicant's earlier proposal, when vibration with large amplitude in the shearing direction is applied to cause prying deformation in the laminated rubber body 116 and apply tensile force to the laminated rubber body 116, the link chain 128, which is always maintained in a tension state between the lower and upper shoe plates 118, 120 due to the restoring compression force, serves to partly support the tensile force, so as to reduce the tensile stress (alternatively referred to as “isostatic stress”) occurring in the laminated rubber body 116 in the laminating direction.